Cam/Bearing failures revisited.

[TR1Hemi]

I have read all of the cam/bearing failures on here, and to be honest, I am now scared of my build. Especially after reading Silvers complete 41 page epic! But on several I have read where people stated HOT oil pressure was fine at 20psi, while that MAY be enough, isn't that is setting the goal a little low. My 97 with 140K, with a quart of tranny fluid to clean up deposits (since I bought it used with 135K on it) still holds 30psi @ on a 100* day without a HV pump, why is 20psi with a HV pump OK on a fresh rebuild? I don't get it. I have also read where people say the cam bearings are "low load", I agree, compared to rods. But even with 100lb seat pressure springs X 10, + 2 half or more open at 150lb each, equals 1300lbs x 1.6 rocker ratio and you have 2000lb MIN, pushing down at any given time, that's 500lbs per cam bearing, and probably more on 2 & 3, things skyrocket when you put 1.8"springs in a 1.64 head". Please tell me if you think I am wrong and why.

[SilverXJ]

Hot oil pressure of 20 is fine for a standard volume pump. Did you verify your 30psi with a mechanical gauge? Factory sensors and gauges are known to be odd.

The cam bearings do not see as much load as you state. They see very little pressure when the valve is closed, basically just the pressure from the oil keeping the lifter up. Who is installing 1.8" springs at 1.64"?

[TR1Hemi]

You know, now that I have gotten some sleep (work nights), the seat pressure isn't even transmitted to the cam lifters, it is held back by the retainer/locks. So was a bogus statement. No I havent checked it with a gauge, but it has seen 2 instrument clusters that read the same.

[TR1Hemi]

I was refering to those who put cam/lifter kit in meant for 258 motors. Since no one makes a "4.0" cam, they are all 258 based, they come with springs designed for a 1.8" installed height, which is not right for a 4.0.

[SilverXJ]

I don't know of anyone that has installed those springs.

[TR1Hemi]

More thoughts...HV oil pump, besides not sitting flat on the block a lot of times, causes cam walk in early style (spring/pin setup), a narrow cam lobe coupled with cam walk equals the lobe edge not riding close enough to the edge of the lifter and not able to spin it, equals lobe/lifter failure, extra drag of lifter/lobe drag, may accelerate bearing failure. Cam walk plus unpolished and sharp cornered cam journals equals bearing failure. Cam bearing clearance issues at play here also. Possible solutions, probably several combined as whole. These aren't in any particular order.

1. Wide lobe, ensures lifter rotation, spreads load at peak.
2. Late style cam retainer plate, or spring/pin to solid pin conversion, reduction in cam walk.
3. Standard pump, these ain't high rpm/race/radical cam motors, reduction in cam walk, and loading of cam bearings.
4. Attention paid to valve spring seat/open pressures, reduced wear on lobes.
5. Oil pump to block mating, adequate oil pressure.
6. Using roller rockers, preferably steel Crowers, to reduce friction, and the required guide plates stabilize valve train.
7. Cam bearing clearance check, increases bearing life.
8. Cam journal polish/coat, increase bearing life, works in concert with number 9.
9. Radiusing of cam journal corners, if there is still slight cam walk, bearing wear reduced, works in concert with number 8.
10. Lifter diameter clearance, use the slightly larger diameter lifters, and ensure they move freely, not only up and down, but rotational.
11. Assembly lube, after degreeing cam, add more, purge air from fuel rail, prime oil system, minutes before installing dizzy, and immediately cranking for the first time.
12. Proper break in.

The problem with all this, I feel the biggest culprits are impossible/the hardest to address. Narrow lobes, cam walk, early style cams.

What is the failure rate in strokers with wide lobes, late style cams with retention plate? It seems to me the only sure fire way to avoid cam failures is a wide lobe late style cam. The problem...1. Is Mopar the only one that makes one? 2. What if you have a early pre 99 block with no retention plate holes? Drill and tap them?

[SilverXJ]

There are no off the shelf late style cams (wide lobes, plate) aside from stock grinds. Mopar sells the spring and pin setup with wide lobes in on the Mopar Performance cams. Any thing else is custom, if you can find someone to find the correct core and grind it for you. I don't thing that the HV pump has bearing on bearing failures, I believe it is mostly due to cam walk. How do guide plates stabalize the valve train? All they do is locate and perhaps stabilize the pushrod.

[TR1Hemi]

IMO, I feel the guide plates keep everything lined up better than the stock square sided lifter fulcrum. As far as the HV pump, it HAS to take more effort to turn. That ADDED to other issues "is the straw that breaks the camels back". Like I said, and I think you have first hand knowledge of, it isn't just ONE thing. I think cam walk, narrow lobes, and the evidence of rough cam journals by some to be the main issues, all the other items, just compound those 3 mains issues.

[TR1Hemi]

I am thinking, because I cant afford a failure, due to time and expense, of going with a late stock dual pattern wide lobe cam, modding my early block for the cam retention plate, and using 1.7 rockers for extra lift. It will still be way better than a stock 4.0, and should be bullet proof. At least until the aftermarket wakes up and makes a late wide lobe cam. Them MAYBE I will do a cam swap.

[Retlaw01XJ]

Silver found a small cam company that could get a wide-lobe cam core. It was recent, within the past 2 months. Search his posts.
A stock oil pump will give good pressure if you keep main and rod bearing clearances between 0.0015 and 0.002". I agree a hv pump will stress the drive components.
I have about 2,000 miles on my '01 build with mild Crower cam and solid pin with 0.014" end play. Hope it lasts!

[TR1Hemi]

I was out looking at my block and old cam earlier, it looks like the extra load of a HV pump is going to drive the cam rearward judging by the gear, which is opposite of what I thought. What stops rearward travel in a non retainer plate setup, the rear cam plug? Can, not installing the rear cam plug in the block allow more walk? How do you measure cam end play?

[TR1Hemi]

and what caused this spot? Also my stock cam bearings were c-shaped, the gap opened up after removal, all 4 were like that, it is a 98 block.

[SilverXJ]

One or two of my failures were with a standard volume pump. Yes, it takes more effort to turn, but I also wanted as much oil to the cam bearings as possible. Some have reported distributor gear wear as there is no direct oiling tot he gear, but I added a squirter for that as well. For some reason Mopar went with a HV oil pump in their strokers too.

What stops rearward travel in a non retainer plate setup, the rear cam plug?

No. The plug should NEVER touch the cam. In a non retaining plate install the rear of the cam gear stops rearward movement.

Can, not installing the rear cam plug in the block allow more walk?

no. If you didn't instal teh rear cam plug oil would pour out of the hole.

How do you measure cam end play?

On the pin setup I put a dial indicator on he rear of the cam with teh timing cover on and moved it back and forth to get the end play number. On the retaing plate setup I initially set end play using feeler gauges outside of the block then rechecked with a dial indicator on the cam.

and what caused this spot?

The round spot? I believe one of the bearings have a second hole, but I do not know why

Also my stock cam bearings were c-shaped, the gap opened up after removal, all 4 were like that, it is a 98 block.

Normal. Most cam bearings are like that. There is a seam you can barely see. I think durabonds may be a full circle, but I can't remember.

[TR1Hemi]

Silver, I meant not installing it deep enough. LOL. But thanks for those other questions.

[SilverXJ]

Silver, I meant not installing it deep enough. LOL.

The cam plug should not touch the back of the cam, so it has no part in setting end play.